The Electric Dipole Moment (EDM) of the neutron is a probe for the violations in the combined Charge-conjugate and Parity reversal symmetry (CP). Many new theories beyond the Standard Model, which aim to unify the fundamental forces and solve the problem of Baryon Asymmetry of the Universe, also predict sizable EDM just lurking around the corner for discovery. Experimental search for the...
The Revolution to our view of nucleon structure and the glue.
The 2015 nuclear physics long-range plan endorsed the realization of an electron-ion collider as the next large construction project after FRIB. The electron-ion collider with its high luminosity (>10^33 cm−2s−1), wide kinematic reach in center-of-mass-energy (20 GeV to 145 GeV) and high lepton and proton beam polarization provides...
Currently, Brookhaven AGS (Alternative Gradient Synchrotron) provides 70% proton polarization with 2 × 1011 intensity. This is achieved by two partial snakes to overcome vertical intrinsic and imperfection resonances and a pair of horizontal tune jump system to overcome the week but many horizontal intrinsic resonances. Further gain was achieved by maintain smaller transverse emittance with...
The Transverse Momentum Dependent Partonic Distributions (TMD-PDFs) and Fragmentation Functions (TMD-FFs) should reveal new properties of the 3-dimensional structure of nucleons and of the quark hadronization process. Many experimental data are now available, much progress has been made in their phenomenological interpretation, future facilities and experiments are being planned. A short...
The 2015 International Workshop on Polarized Sources, Targets & Polarimetry took place at the Ruhr-University Bochum on September 14th - 18th 2015. The Workshop has been a tradition for more than 20 years, moving between Europe, USA and Japan. The XVIth International Workshop on Polarized Sources, Targets and Polarimetry (PSTP 2015) addresses the physics and technological challenges related to...
The ground state masses of the heavy-light pentaquark baryons like θ0c, N0c, Ξ0c and θ+b, N+b, Ξ+b for different spin states have been investigated in the frame work of diquark-diquark-antiquark configuration where the light quarks are supposed to combine to form diquarks. A composite fermion model of quasi particle has been employed to describe the diquark in an analogy of state of an...
We present the first lattice-QCD calculation of the isovector polarized parton distribution functions (both helicity and transversity) using the large momentum effective field theory (LaMET) approach for direct Bjorken-x dependence. We first review the detailed steps of the procedure in the unpolarized
case, then generalize to the helicity and transversity cases. We also derive a new...
In this talk I will present an overview of recent developements on gluon transverse momentum dependent (TMD) parton distributions. Such non-perturbative objects might be feasible in high-energy proton collisions at the LHC, but also at a future Electron-Ion Collider (EIC). Most interestingly, due to the gluon’s transverse momentum the gluon can have a linear polarization which is encoded in a...
We discuss the measurements of parity-violating asymmetries in DIS region (PVDIS) using SoLID spectrometer at JLab Hall A in the 12 GeV era. Mea-surements with polarized electron beam on unpolarized deuteron and proton targets have been approved with an A rating. The deuteron measurement aims to measure weak mixing angle sin2(θW) with precision of ± 0.0006 as well as access a fundamental...
The large spin dependence of the absorption cross section for neutrons by 3He gas provides a method to polarize neutron beams. For certain applications, such polarized 3He-based neutron ”spin filters” have advantages over conventional neutron optical polarizing methods. Spin filters operate at all neutron wavelengths, can cover a large angular range and/or a large energy range, and decouple...
Spin tilt, about 16 and 9 degrees from vertical, in respectivley RHIC Blue and Yellow rings, has been observed during 255 GeV polarized proton RHIC run 13, at the p-carbon polarimeters, about 70 m away from IP12. A possible origin of this y-normal tilt is in a spin rotation angle defect at one of, or both, RHIC helical snakes. This possible cause has been investigated by scanning the rotation...
At Jefferson Lab, a Polarized 3He Target has been used as an effective polarized neutron target for studying nucleon spin structure. For the 12 GeV program at JLab, the first stage upgrade of the target aim to increase factor of three the performance (Figure-of-Merit) and reach a systematic uncertainty of polarimetry below 3%. During the 6 GeV era, the target polarization was measured by two...
The Relativistic Heavy Ion Collider (RHIC) has provided polarized proton-proton collisions to
experiments for the past decade with beam polarizations of P=55% at beam energies of up to 255 GeV.
The polarization of the proton beams is measured through spin dependent elastic scattering off a
polarized hydrogen jet target and similarly monitored with Carbon fiber targets several times
throughout...
We report the status of our lattice QCD calculation of the quark flavor decomposition of the proton spin. The quark spin calculation is recently carried out from the anomalous Ward identity (AWI) with chiral fermions and is found to be small mainly due to the large negative pseudoscalar coupling in the AWI which may help to solve the proton spin crisis. We also report a scheme of constructing...
I shall report on the glue-momentum fraction in the proton, based on the covariant decomposition, and the necessary perturbative calculation to convert them from the lattice regularization to MS-bar scheme at 2 GeV. The strategy of the lattice simulation for the spin decomposition based on Xiang-Song Chens scheme, and the preliminary result of the glue spin component, will also be reported.
The RHIC Run16 included 5 weeks of d-Au Energy Scan. We employed the Polarized Atomic Hydrogen Gas Jet Target (HJET, the absolute polarimeter for RHIC pp program) to measure elastic scattering of polarized protons on deuterium and Gold nuclei at four energies: 10 GeV, 19 GeV, 31 GeV, and 100 GeV. The measurements were performed in parallel with the main RHIC program. Analyzing power, as a...
The COMPASS experiment (SPS, CERN) covers a broad range of physics aspects in the field of hadron structure and spectroscopy. Particular focus is given to the exploration of the transverse spin structure of the nucleon via the study of spin (in)dependent azimuthal asymmetries measured in semi-inclusive deep inelastic scattering (SIDIS) and Drell-Yan
(DY). Within QCD parton model approach,...
The observation of the transformation of a neutron into an antineutron would reveal that B-L symmetry is broken and thus that dynamics beyond the Standard Model exists. Notably it would establish that neutrons can act as their own antiparticles, making the process a hadronic analog to neutrinoless double beta decay. I will discuss the role of spin, highlighting how external fields or sources...
Studies of the Transverse Momentum Dependent parton distributions (TMDs) of the nucleon in the valence quark region have emerged as one of the flagship physics programs of the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. The TMDs of the nucleon describe the spin-dependent, three-dimensional distributions of its constituent partons in momentum space. The simplest and...
I examine some of the complications involved when combining (matching) TMD factorization with collinear factorization to allow accurate predictions over the whole range of measured transverse momentum in a process like Drell-Yan. Then I propose some improved methods for combining the two types of factorization. (This talk is based on work reported in arXiv:1605.00671.)
The COOler SYnchrotron is at the forefront of precise spin dynamics. The facility can accelerate polarized protons at up to 3.7 GeV/c. Numerous specialized devices such as electron coolers, a stochastic cooler and more recently a superconducting solenoidal snake make this accelerator complex unique. As new opportunities and challenges come into perspective of the facility, it calls in...
The COMPASS experiment at the CERN SPS has taken data with a polarised muon beam scattering off a polarised NH3 target in 2007 and 2011 and scattering off a 6LiD target from 2002-2004 and 2006. The 2006 measurement increases the statistics from 2002-2004 by roughly a factor of two. For the measurement in 2011 the beam energy has been increased from 160 GeV to 200 GeV thus higher values of Q2...
The Bochum polarized target group is involved in the fixed target experiments COMPASS at CERN and baryon spectroscopy at ELSA and MAMI. The experiments at Bonn and Mainz are focused on the study of the nucleon resonance region with polarized beam and target with 4 detection system. The focus of the COMPASS experiment is the study of hadron structure and hadron spectroscopy with high intensity...
Physics beyond the standard model involving heavy particles can be parameterized by effective field theories of new interactions between the standard model particles. The new interactions involving quarks and gluons are, however, dressed by the strong interactions before they can be observed as low energy properties of hadrons. Lattice QCD is currently the only systematically improvable...
We present a lattice QCD calculation of transverse momentum dependent parton distribution functions (TMDs) of protons using staple-shaped Wilson lines. For time-reversal odd observables, we calculate the generalized Sivers and Boer-Mulders transverse momentum shifts in SIDIS and DY cases, and for T even observables we calculate the transversity related to the tensor charge and the generalized...
The construction of the PAX installation was inspired by the idea to make a beam of polarized antiprotons available for future experiments with stored antiproton beams. A spin filtering experiment with internal polarized proton storage cell target was realized using the PAX low-beta installation at COSY. The results of this measurement are in perfect agreement with the FILTEX experiment. Spin...
Most of the activity in the Polarized Target Lab. at the University of Virginia has centered around the preparation of polarized targets for experiments at Fermilab and TUNL(Duke U.), while investigating some special features for experiments at JLab. For experiment E1039 at Fermilab a magnet/ 4He refrigerator combination that had been in storage for 15 years has been modified and restored to...
The PEPPo (Polarized Electrons for Polarized Positrons) experiment at Jefferson Lab (Jlab) investigated a new approach of developing polarized positron source. The PEPPo concept relies on the production of polarized e-/e+ pairs from the bremsstrahlung radiation of a longitudinally polarized electron beam interacting within a high Z conversion target....
In this talk we will discuss recent progress in nucleon structure using Lattice QCD simulations at or near to the physical value of the pion mass. Main focus will be given in observables such as the nucleon axial charge and the first moments of parton distributions, for both the valence and sea quark contributions, and discuss their implications on the spin content of the nucleon. We will...
A discussion of dynamic orientation using optimized radio frequency (RF) irradiation produced perpendicular to the holding field is presented for the spin-1 system required for tensor polarized fixed target experiments. The rate equations are solved numerically to study a semi-saturated steady-state resulting from the two sources of irradiation, microwave from the DNP process and the...
There exist new polarized structure functions b1−4 for spin-one hadrons such as the deuteron. These functions probe very different nature of hadron spin physics from the longitudinally polarized distributions measured by g1 for the nucleon. The twist-two structure functions b1 and b2 are expressed by tensor polarized parton distribution functions, which indicate unpolarized parton...
Precision measurements on the transverse momentum dependent hadron multiplicities in semi-inclusive deep inelastic scattering is, with unpolarised azimuthal asymmetries, crucial in the determination of the quark intrinsic transverse momentum and in TMD evolution studies. COMPASS has measured differential multiplicities of hadrons using a deuteron target in a four-dimensional space. This data...
Tensor-polarized parton distribution functions are new quantities in spin-one hadrons such as the deuteron, and they could probe new quark-gluon dynamics in hadron and nuclear physics. In charged-lepton deep inelastic scattering (DIS), they are studied by the twist-two structure functions b1 and b2 [1, 2]. The HERMES collaboration found unexpectedly large b1 values than a naive theoretical...
The University of Virginia (UVA) polarized target group in cooperation with Los Alamos National Lab has designed and built a solid polarized target system for the anticipated Fermilab E1039 Drell-Yan experiment. We report the completion of refurbishing the 5T superconducting Oxford magnet and 1K evaporation refrigerator. Recent tests performed at UVA will be presented.
To obtain sensible information about hadronization in the current region from experiment, it is essential to understand the kinematical range of applicability of the formalism of fragmentation functions, which is often overlooked in phenomenological applications. In this talk, I will describe how one may identify the current region and argue that at low Q2 the distinction between current and...
With Jefferson Lab’s upgrade to a 12 GeV electron beam comes a new, improved detector system in Hall B: CLAS12. The dynamically polarized solid target, which was a mainstay of double-polarized scattering experiments in the 6 GeV era, must also be rebuilt to accommodate the new constraints. The new target and its horizontal refrigerator will fit in a space restricted by the new CLAS12 5 T...
An Electron-Ion Collider (EIC) is proposed as the first lepton- hadron collider in the world with both beams polarized. The envisioned nuclear physics program requires high polarizations, long polarization lifetimes, and unprecedented capabilities of polarization control in both collider rings. The electron polarization must be longitudinal at the interaction points while the light ion...
We present COMPASS results on the longitudinal double-spin asymmetry, Ap1, and the spin dependent structure function of the proton, gp1, in the quasi-real photoproduction regime. Data were collected by scattering a longitudinally polarised
muon beam off a longitudinally polarised proton target. Two data sets with a beam energy of respectively 160 and 200 GeV were taken, which improve, once...
Measurements of the nucleon spin-dependent structure functions have provided powerful tools to test the validity of effective theories of Quantum Chromodynamics (QCD). The neutron spin structure functions, gn1 and gn2, and the proton spin structure function, gp1, have been measured over a wide kinematic range. However, the proton spin structure function, gp2, is mostly unknown. Recently an...
The HDice frozen spin, solid Hydrogen-Deuteride target has been used in recent years with photon beams in Jefferson Lab’s Hall B. With the recent upgrade of the Hall’s CLAS detector and Jefferson Lab’s CEBAF accelerator come new physics opportunities to study the 3D structure of the nucleon. In this vein, there are presently three A-rated experiments which have been designated as having a...
The Gerasimov-Drell-Hearn (GDH) sum rule, as a fundamental sum rule for real photon absorption, relates the anomalous magnetic moment to the spin structure of the nucleon. The generalized form of GDH sum rule extends this relation to finite four-momentum transfer squared (Q2). Jefferson Lab experiment E97-110 was performed with a High Resolution Spectrometer (HRS) and a septum magnet in Hall A...
An electron-ion collider is being considered as a next large facility for nuclear physics studies in United States. Using polarized beams of electrons, protons, and, possibly, light ions is an essential requirement for this collider. eRHIC, the electron ion collider designed in BNL, takes a big advantage of using existing world-class polarized proton facility RHIC. The polarized electron beam...
Three A-rated proposals to study the 3D structure of the nucleon with the CLAS12 detector require a transversely polarized target [1]. A minimal R B × dL is needed to limit beam deflection by the transverse holding field of such a target. At the same time, the axial field of the CLAS12 central solenoid must be canceled over the same region. Finally, adequate field uniformity to allow NMR...
We discuss a new hard pole contribution to the transverse- momentum weighted single-transverse spin asymmetry in semi inclusive deep inelastic scattering. We perform a complete next-to-leading order calculation of the Ph⊥-weighted cross section and show that the new hard pole contribution is required in order to obtain the complete evolution equation for the Qiu-Sterman function.
We have developed a circular electron accelerator that is free of intrinsic resonances. This lattice
could be placed in the existing RHIC tunnel and accelerate electrons from 100 MeV to 20 GeV avoiding all major polarization loss usual in such machines.
We present a point-by-point determination of the Sivers parton distribution function. The extraction is similar to the one already performed for the transversity distribution, namely it is based on the simultaneous use of proton and deuteron semi-inclusive deeply inelastic scattering data. Since the Sivers asymmetries involve the ordinary unpolarized fragmentation functions, SIDIS data are...
In scattering experiments that use targets relying on dynamic nuclear polarization (DNP), target materials must be irradiated using microwaves at a frequency determined by the difference in the nuclear Larmor and electron paramagnetic resonance (EPR) frequencies. Since the resonance frequency changes with time as a result of radiation damage, the microwave frequency should be adjusted...
Proton spin is investigated in chiral effective field theory through an examination of the singlet axial charge, a0, and the two non singlet axial charges, a3 and a8. Finite-range regularization is considered as it provides an effective model for estimating the role of disconnected sea-quark loop contributions to baryon observables. Baryon octet and decuplet intermediate states are included to...
In the context of the nucleon spin structure the Sivers effect, which describes the correlation between the nucleon spin and the orbital motion of partons, may give information on the gluon orbital angular momentum, one of the missing elements in th nucleon spin sum rule. The gluon Sivers function can be accessed via the photon-gluon fusion process. To enhance the fraction of photon-gluon...
In recent years, measuring azimuthal asymmetries in semi -inclusive deep-inelastic scattering (SIDIS) off polarized targets emerged as a powerful tool to investigate the nucleon spin structure, one of the main objectives of the COMPASS physics program. The two-stage COMPASS spectrometer at the CERN SPS is characterized by a large acceptance and a broad kinematic coverage. It makes use of a...
The Dynamic Nuclear Polarization (DNP) is an efficient technique to enhance the nucleus polarization by the so-called ‘Radiation doping’ or ‘Radical chemically doping’ methods in the field of polarized solid targets for their use in nuclear and particle physics experiments. Polymer materials have been used since 1994 due to the advantage of its easy handling at room temperature and shape...
The transversity distribution was recently extracted from deep inelastic scattering processes producing hadron pairs in the final state because it is involved, together with a specific chiral-odd di-hadron fragmentation function, in the elementary mechanism that generates a transverse-spin asymmetry in the azimuthal distribution of the detected hadron pairs. The same elementary mechanism was...
Electric Dipole Moments (EDM) of elementary particles including hadrons, are considered as one of the most powerful tools to discover CP violation beyond the Standard Model. Such CP violating mechanisms are required to explain the dominance of matter over anti-matter in our universe. Up to now experiments concentrated on neutral systems (neutron, atoms, molecules). Storage rings offer the...
The contribution to the spin of the proton from its constituents has been one of the unresolved questions in nuclear physics. The longitudinal spin program at STAR is exploring a wide range of measurements to determine the gluon helicity distribution inside the proton. The inclusive jets and pions in the kinematic range accessed by RHIC are dominated by quark-gluon and gluon-gluon scattering...
Electromagnetic polarizabilities are important parameters for understanding the interaction between photons and hadrons. For most hadrons these quantities are poorly constrained experimentally since they can only be measured indirectly. Lattice QCD can be used to compute these quantities directly in terms of quark and gluons degrees of freedom, using the background field method. We present...
In light of the recent recommendation by the Nuclear Science Advisory committee to construct a U.S. based Electron Ion Collider (EIC), the spin community at the Relativistic Heavy Ion Collider has developed a program of must-do experiments to be run during the period leading up to the turn on of the EIC. These experiments will utilize the unique capabilities of the world’s only polarized...
In a few short years, the Relativistic Heavy Ion Collider (RHIC) will embark on detailed studies of the Quark Gluon Plasma with a major new jet-optimized detector known as sPHENIX. On the same timescale, the recent RHIC Cold QCD plan outlines a compelling program of key measurements in spin-polarized p+p and p+A collisions that can be realized on the road to an Electron Ion Collider (EIC). To...
Over the last decade, theoretical and experimental engagement of the oft challenging phenomena of nucleon transverse-spin has unlocked tantalizing opportunities for new insight into nucleon structure and more expansive formulations of QCD, e.g. with higher dimensions in momentum space. The RHIC experiments continue this exploration through an array of measurements from high-energy...
Understanding the proton spin structure in terms of quark and gluon degrees of freedom is one of the key open questions in the field of hadron physics. Gluon helicity, ∆g(x), related measurements play an important role in solving this “Spin Puzzle”. The polarized proton+proton collisions at the Relativistic Heavy Ion Collider provide unique opportunities for studying ∆g(x) by accessing it via...
A permanent electric dipole moment (EDM) of the isotope 129Xe would imply a breakdown of both parity P and time reversal symmetry T and, through the CPT theorem, a breakdown in CP, the combined symmetries of charge conjugation C and parity P. Our goal is to improve the present experimental limit (dXe < 3 · 10−27 ecm) by about three orders of magnitude. The most precise EDM limit on diamagnetic...
The 2015 Nuclear Physics Long Range Plan has endorsed the realization of an electron-ion collider as the next large construction project in the US after FRIB. The machine is planned to be high luminosity, exceeding 10^33 cm−2 s−1, with highly polarized electron and proton/light ion beams, wide kinematic reach and ability to collide a variety of hadron species from p to Pb. The facility and...
One of the main goals of the RHIC spin program is the determination of the gluon helicity contribution to the proton spin. This can be accessed by measuring double spin asymmetries (ALL) of pion production at mid-rapidity in longitudinally polarized proton collisions with the PHENIX experiment. The ordering of the asymmetries with the charge of the final state pions can in addition directly...
Two-particle angular correlations have long been used as an observable for measuring the initial-state partonic transverse momentum kT . Sensitivity to this small transverse momentum scale allows nonperturbative transverse momentum dependent (TMD) effects to be probed in high pT dihadron and direct photon-hadron correlations. The observable pout, the out-of plane transverse momentum component...
The "flexible" parametrization of quark and gluon Generalized Parton Distributions (GPDs), based on spectator models and Regge behavior, will be presented. The Chiral Even GPDs, constrained by nucleon form factors and PDFs, determine deeply virtual Compton scattering amplitudes and are compared with cross section and polarization data. The Chiral Odd GPDs, including "transversity", contribute...
The transversity distribution is a fundamental component of the spin structure of the nucleon, and is only loosely constrained by existing semi-inclusive deep inelastic scattering data. The di hadron interference fragmentation function (IFF), which describes the fragmentation of transversely polarized quarks, is expected to give rise to spin-dependent di-hadron correlations in p↑+p collisions....
An overview of the form factor programme of the A1 Collaboration at MAMI is given. Results on the electromagnetic form factors of the proton measured with elastic electron scattering at four-momentum transfers Q2 between 0.003 and 1 GeV2/c2 are reported, which allow an extraction of the electric and magnetic radii and a determination of the two-photon exchange correction. The analysis of...
One of the main interest of nuclear physics is to understand nuclear properties based on bare nuclear forces. Recently, it is indicated that the three-nucleon forces (3NFs) is essential to clarify various nuclear phenomena. Few-nucleon scattering at intermediate energies (∼ 100 MeV/nucleon) is one of good approach to investigate dynamical aspects of 3NFs. In the last decade study of...
Measurements of asymmetries in the inclusive and exclusive production of Lepton pairs (DY pairs) in collisions of non- polarized, longitudinally and transversally polarized proton and deuteron beams are suggested to be performed at the NICA collider of the JINR using the specialized Spin Physics Detector. These measurements can provide an access to all leading twist collinear and TMD PDFs of...
We present a lattice QCD calculation of the strange quark contribution to the proton’s magnetic moment and the charge radius at the physical pion mass. We perform a model independent extraction of the strange magnetic moment and strange charge radius from the electromagnetic form factors in the momentum transfer range of 0.051 GeV2 <∼ Q 2 <∼ 1.31 GeV2. The finite lattice spacing and finite...
A Monte-Carlo code of jet generation by a transversely polarized quark is proposed. It is based on the recursive splitting of a string, like in the symmetric Lund fragmentation model, together with the 3P0 model of quark-antiquark pair creation. The code involves a complex mass parameter, in addition to the usual Lund parameters. The Collins effect is obtained and the related asymmetries,...
Starting with the discovery of EMC that quarks are not the only building blocks of the nucleon spin its structure has been a topic of intense studies for numerous experiments. With precision measurements of quark and gluon polarisations by SMC, HERMES, COMPASS, STAR and PHENIX collaborations we are closing to an answer. The quark contribution is already determined with good accuracy and...
We investigated the cross section and the associated spin asymmetries for vector boson (W^\pm/Z_0/γ*) production in polarized proton-proton collisions at tree level within the TMD factorization formalism. Besides the well-known Sivers function f_1T, the single transverse asymmetry could also probe the transversal helicity distribution g_1T via the parity-violating nature of W/Z_0 production....
Measurements of single single spin asymmetries (AN ) in spin-polarized proton-proton collisions are a relatively straightforward experimental measurement that offers insight into the structure of the proton. However, AN integrates over both initial and final state effects, making the interpretation of a single measurement in terms of the underlying physical processes difficult. The RHIC...
In the polarized Drell–Yan experiment at the COMPASS facility in CERN a pion beam with momentum of 190 GeV/c and intensity about 108 pions/s interacted with transversely polarized proton target. The muon pair produced in Drell–Yan process was detected. The measurement was done in 2015 as the 1st ever polarized Drell–Yan experiment. The solid-state NH3 as polarized proton target was polarized...
Preparation of the research program at the Nuclotron and the future NICA collider facility is carried out during the last years. The problems of design, construction and tests of new polarized ion source (protons and deuterons), reconstruction of a front end part of the existing linac LU-20, preparation of polarimeters these are current works have been performed within the last few months. In...
Searches for permanent electric dipole moments (EDMs) are sensitive to time-reversal, parity, and charge-parity (CP) violation, and, as such, are excellent probes for physics beyond the Standard Model. 225Ra (t1/2=15d, I=1/2) is a particularly attractive system to use for an EDM search because its large nuclear octupole deformation makes it uniquely sensitive to CP violating interactions in...
In recent years, the quasi parton distribution has been introduced to extract the standard parton distribution functions by lattice QCD simulations. The quasi and standard distribution share the same collinear IR singularity and the quasi distribution can be factorized into the normal distribution with perturbative matching factors. The quasi parton distribution is known to have power-law UV...
The STAR experiment at RHIC has provided significant contributions to our understanding of the structure of the proton. The STAR experiment is well equipped to measure W± → e± +ν in √s = 510 GeV longitudinally polarized p + p collisions at mid rapidity (|η| < 1). The longitudinal single spin asymmetry in W production, AL, measured as a function of decay positron (electron) pseudo-rapidity η...
We will review the experimental program dedicated to photon electroproduction running in the Hall A of Jefferson Laboratory. First we will talk about the latest results of the E00-110 experiment running in 2004, published in Phys.Rev.C last year. Then we will present new results of photon electroproduction cross sections in the valence region (xBj=0.36) at three Q2-values (1.5, 1.75 and 2...
QCD Confinement precludes experiments from resolving colored quarks in order to understand the strong forces between them, however, polarized DIS experiments uniquely provide a clean measurement of observables used in determining an average color Lorentz force on the struck quark. Within the operator product expansion framework, the twist-3 matrix element, dp2 =Rx2(2g1+3g2)dx, is proportional...
There have been many efforts to access the transverse momentum dependent parton distributions (TMDs) by using the semi-inclusive deep inelastic scatterings (SIDIS) processes. The next generation SIDIS experiments with the proposed Solenoidal Large Intensity Device (SoLID) in Hall A at Jefferson Lab, will fully utilize the great physics potential of the 12-GeV energy upgrade by combining high...
We will discuss the new E1039 experiment at Fermilab to measure the single spin asymmetry of the Drell-Yan process on a transversely polarized target. This measurement can be used to determine the sign and magnitude of the Sivers asymmetry. A non-vanishing Sivers asymmetry requires a non-zero orbital angular momentum contribution of the sea quarks to the nucleon spin. This will be the first...
Investigation of GPDs and TMDs represents one of the major goals of the COMPASS-II program. Together, GPDs and TMDs provide the most complete description of the partonic structure of the nucleon. GPDs are experimentally accessible via lepton-induced exclusive reactions, in particular DVCS and DVMP. At COMPASS, these processes are investigated using a 160 GeV high intensity muon beam and a 2.5...
The measurement of the single spin asymmetry of parity violating W boson production in longitudinally polarized proton collisions provides unique and clean access to the light sea quark helicity distributions. The W boson couples only to left handed quark and right-handed anti quark, and hence one can directly relate the charge of the W with initial state quark flavors. The PHENIX experiment...
We consider the process of DIS on a (polarized) deuteron with detection of a nucleon in the nuclear fragmentation region (spectator tagging). Its advantages and complications compared to inclusive scattering are discussed with emphasis on the method of pole extrapolation to obtain on-shell nucleon structure in a model independent way and the issue of nuclear final-state interactions (FSIs)....
A COMPASS (Common Muon Proton Apparatus for Structure and Spectroscopy) group researches hadron structure and hadron spectroscopy with high intensity muon and hadron beams. In 2015, COMPASS performed a polarized DY experiment to measure transverse momentum dependent parton distributions. A π− beam with momentum 190 GeV/c and a transversely polarized proton target (PT) were used.
The COMPASS...
In the Spallation Neutron Source based neutron Electric Dipole Moment (SNS nEDM) experiment, spins of polarized ultracold neutrons and polarized 3He will be manipulated in a 0.3 - 0.5 K superfluid 4He bath. Measurements will be made using two different modes: free precession and critical dressed spin. In the former, both spin species undergo a π/2 flip and then precess at their Larmor...
Lattice quantum chromodynamics is well suited for evaluating matrix elements of local operators and so naturally provides the moments of distribution functions as defined through the operator product expansion procedure. Unfortunately, the reduced symmetry of the (hypercubic) lattice means that as the continuum limit is approached, the matrix elements of higher spin operators evaluated on the...
The net contribution of the strange quark spins to the proton spin, ∆s, can be determined from neutral current elastic neutrino-proton interactions at low momentum transfer combined with data from electron-proton scattering. This is because the probability of neutrino-proton interactions depends on the axial form factor, which represents the spin structure of the proton and can be separated...
The Collaboration measures the integrand of the GDH integral for the deuteron
below 20 MeV. Mono-energetic and polarized intensive gamma rays produced by
HIγS at Duke Free Electron Laser Laboratory are incident on longitudinally
polarized deuteron target, using HIFROST. Neutrons from photodisintegration
reaction on...
We show that Generalized Transverse Momentum Distributions (GTMDs) and Generalized Parton Distributions (GPDs) can be connected by Lorentz Invariant Relations (LIRs). The GTMDs have an explicit dependence on the partonic intrinsic transverse momentum and the case of unpolarized quarks in a longitudinally polarized proton is known to connect to Orbital Angular Momentum (OAM) through the GTMD...
We study the transverse single-spin asymmetry with a sin ϕS modulation in semi-inclusive deep inelastic scattering after the transverse momentum of the final state hadron is integrated out. In particular, we consider the case in which the transverse momentum of the final state hadron is integrated out. Thus, the asymmetry is merely contributed by the coupling of the transversity distribution...
Authors: R. Talman, Cornell University; J. Grames, R. Kazimi, M. Poelker, R. Suleiman, Thomas Jefferson National Laboratory; B. Roberts, University of New Mexico
It is explained how the CEBAF 123 MeV injection line can serve as one big Stern-Gerlach (S-G) polarimeter measuring the polarization state of the injected beam. No physical changes to the line are required and (though not optimal)...
Precision measurements of the anomalous magnetic moment of the muon, aµ ≡ (gµ − 2)/2, provide an excellent test of the Standard Model with sensitivity to physics beyond the Standard Model. The most recent measurement of aµ at Brookhaven National Laboratory (E821) differs from the Standard Model prediction by roughly 3.5 standard deviations. Currently under construction at Fermilab is a new...
In 2015 the first collisions between polarized protons and nuclei occurred at the Brookhaven Relativistic Heavy Ion Collider (RHIC). This talk will present preliminary measurements of the forward transverse single spin asymmetries AN in p+p and p+A collisions with CM energy of √sNN = 200 GeV. Photons from π0 decays were measured with the STAR FMS electromagnetic calorimeter that had been...
The existence of intrinsic quark and antiquark in the nucleon and their asymmetric distribution were suggested some time ago, but there is still no convinced evidence. We investigate the difference between quark to Λ and Λ longitudinal spin transfers in the light-cone quark-spectator diquark model at COMPASS, E665 and HERMES kinematic domains. Such a difference can provide additional...
The J-PARC E34 experiment aims to measure the anomalous magnetic moment (g-2) and electric dipole moment (EDM) of the positive muon with a novel technique utilizing an ultra-cold muons accelerated to 300 MeV/c and a 66 cm-diameter compact muon storage ring without focusing electric field. This measurement will be complementary to the previous BNL E821 experiment and upcoming FNAL E989...
Polarized 3He gas targets have been used successfully at Jefferson Lab (JLab) for a number of electron scattering experiments to study 3He spin physics and more importantly, as an effective polarized neutron target, to study the neutron spin physics, including longitudinal and transverse spin structure and 3-d structure. The performance of the JLab target reached...
In principle, resonant cavities can be excited by magnetic moments of a polarized beam, thus allowing to determine the beam’s polarization by measuring the amplitude of the resonating cavity’s fields. The steady state field amplitude can be determined by calculating the energy transferred from the beam to the resonator’s fields. Analytic formulas for different cavity modes are obtained by...
A high luminosity polarized electron ion collider offers an unprecedented probe of the QCD dynamics of hadron and nuclear structure. I will present the JLEIC accelerator, interaction region, and detector design in the context of its impact on spin physics. The ion beams will include longitudinally and transversely polarized protons and 3He, as well as both vector and tensor polarized...
We report our recent lattice calculation of hadronic light-by-light contribution to muon g−2 using our recent developed moment method. The connected diagrams and the leading disconnected diagrams are included. The calculation is performed on a 483 × 96 lattice with physical pion mass and 5.5 fm box size. We expect sizable finite volume and finite lattice spacing corrections to the results of...
The first high energy polarized proton-nuclei collisions at RHIC in 2015 give us opportunities to study unexplored reaction mechanisms of hadron production in the forward region. In PHENIX, single transverse spin asymmetries (AN s) of forward (6.8 < η < 8.8) neutron production in √sNN = 200 GeV p+Al, and p+Au collisions are measured, and an unexpected strong A dependence in AN is found. The...
In order to investigate the proton radius puzzle, the PRad experiment (E12-11-1062) was recently performed with 1.1 and 2.2 GeV unpolarized electron beam on a windowless H2 gas flow target in Hall B at Jefferson Lab. The experiment aims to extract the electric form factor of proton in an unprecedented low four-momentum transfer squared region, Q2 =2 × 10−4 − 0.1 (GeV/c)2, with a sub-percent...
The Universe around us consist mainly of matter although it is assumed that in the Big Bang an equal amount of antimatter has been produced. The Standard Model prediction for the proportion for the number of the baryons and antibaryons differs from the Astrophysical observations by eight orders of magnitude. To explain this phenomenon, which is usually called the Baryon Asymmetry of the...
Historically, large transverse single spin asymmetries (SSA) have been measured in protonproton collisions which are nearly independent of the collision energy. At RHIC, both PHENIX and STAR experiments measured SSA’s in neutral pion and η meson production from p + p collisions, in central and forward pseudo rapidity regions (η). The central η measurements were found to be consistent with zero...
The large-area planar Drift Chamber 5 (DC05) was constructed in 2014 and 2015 at the University of Illinois and Old Dominion University to replace an aging detector in COMPASS at CERN. It was assembled at CERN and installed to the large angle spectrometer of COMPASS during the spring of 2015. It has a sense-wire to sense-wire pitch of 8 mm, an active area of approximately 249x209 cm2, and an...
In the main frame of the experiment programs on COSY ring, more precise measurements
on spin dependent cross sections for the spin filtering process (PAX experiment)
and on the Time Reversal Invariance test at COSY (TRIC), required the upgrading of
the gaseous internal polarized target and the whole system of it: the pABS (polarized
atomic beam source), the cell (openable) and the diagnostics...
In two π + W induced Drell-Yan experiments at CERN and Fermilab, angular distributions of the resultant dimuons showed a violation of the Lam-Tung relation, a perturbative QCD, “Callan-Gross-like” relationship between the polar and azimuthal angles made by the initial hadronic plane and final state dimuon plane in the Collins-Soper frame. At these energies, the violation manifests itself as a...
Meson photoproduction is an important tool in the study of baryon resonances. The spectrum of broad and overlapping nucleon excitations can be greatly clarified by use of polarization observables. The N* program at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS) includes experimental studies with linearly- and circularly-polarized tagged photon beams, longitudinally- and...
Spin-orbit coupling plays an important role in nuclear structure and reactions. Scattering asymmetry in differential cross section of elastic scattering, i.e. analyzing power, is a a direct consequence of the spin-orbit coupling between the proton and the target nucleus. Extensive experimental data exist for stable nuclei on this subject, while almost no experimental attempts have been made...
Searches for permanent electric dipole moments (EDMs) bear the potential to reveal physics beyond the Standard Model. The JEDI (Jülich Electric Dipole moment Investigation) collaboration explores the prospects for measurements of charged nuclei, i.e. proton, deuteron and Helium-3 EDMs in dedicated storage rings. As an intermediate step, a first direct measurement of the deuteron EDM is planned...
Longitudinal spin asymmetries have been a prime source of information on the nucleon’s spin structure for several decades. In order to match the precision of currently available and future data taken at Compass, JLab, RHIC and a future EIC, it is of great importance to understand higher order corrections in QCD. We review the current status of higher order QCD corrections for longitudinally...
Deeply virtual Compton scattering (DVCS) has received a lot of attention as a process to understand the transverse structure of nucleons. One feature of this cross section is the contamination from the Bethe Heitler piece, which results in cumbersome expressions. In this talk, I will discuss the helicity amplitude formalism in DVCS and its relevance in phenomenological applications.
An exploratory phase to evaluate performances of COMPASS-II data processing using Blue Waters was granted from May 2016 through November 2016. The evaluation of COMPASS software and data transfer rates between CERN and Blue Waters is currently in full swing at Blue Waters and is extremely promising. A suitable data production model must be continuously improved to meet the expectations of raw...
At COMPASS DVCS and DVMP processes are studied in order to probe the partonic structure of the nucleon by constraining GPD models. Extending beyond semi-inclusive deep inelastic scattering, the measurement of lepton-induced exclusive reactions enables the study of GPDs, which ultimately reveal the three dimensional picture of the nucleon and the decomposition of its total angular momentum. The...
In order to understand the strong interaction in the non perturbative region, the excitation spectrum of nucleons is one of the most important tools to use. Recent experiments using the Crystal Ball/TAPS setup at the MAMI accelerator in Mainz, Germany continue to study these properties and the excitation spectrum with meson photoproduction. Electromagnetic excitations of the proton and neutron...
The JEDI (Jülich Electric Dipole Investigations) Collaboration aims for measuring the electric dipole moments (EDMs) of charged particles (deuterons and protons) at the COoler SYnchrotron (COSY). To make this possible, a new, high precision novel waveguide RF Wien filter is planned to be integrated in COSY to modulate the spin of deuterons and protons. With a Wien filter, the force of the...
The neutron absorption in eV region is dominated by capture process via well-resolved compound states. The breaking of the spatial inversion symmetry is known to be largely enhanced in p wave compound resonances according to the interference in the entrance channel between neighboring resonances with different angular momentum of incident neutrons. The entrance channel interference naturally...
Although being a higher-twist contribution, the transverse response was assumed to be responsible of the large π0 electroproduction cross sections measured by the Hall A and CLAS collaboration. However no Rosenbluth separation has been performed yet to verify this assumption. We will present new results of π0 electroproduction cross sections in the valence region (xBj=0.36) at three Q2 -values...
In recent years, the NNPDF Collaboration has developed a new methodology to determine the parton distribution functions (PDFs) of the proton. This is based on a Monte Carlo sampling and representation of PDFs, a parametrization of PDFs based on neural networks, and closure tests for a full characterization of procedural uncertainties. The aim is to provide minimally biased parton sets in which...
The observation of an electric dipole moment (EDM) or its upper limit at levels near
10‒29 e cm would either uncover new forms of CP violation or put at risk many models that seek
to explain the excess of matter over anti-matter in the present universe. This talk presents new
results on studies of the feasibility of conducting an EDM search using a polarized deuteron beam
circulating in a...
The sPHENIX detector is a proposed new detector at the Relativistic Heavy Ion Collider (RHIC). The sPHENIX physics program focuses on jets and hard probes of the quark gluon plasma (QGP). The sPHENIX detector will also have the ability to study jets in polarized proton-proton and proton-nucleus collisions and could also serve as part of a detector for an electron ion collider. The proposed...
We report on the first measurements of the two- and three-body photodisintegration of longitudinally polarized 3He using a circularly polarized γ-ray beam at the incident photon energies of 29.0 MeV and 16.5 MeV, respectively. The experiments were carried out at the High Intensity γ-ray Source facility located at the Triangle Universities Nuclear Laboratory. A highpressure 3He target,...
Pion-Induced reactions offer an unique opportunity to test the Quantum ChromoDynamics improved quark-parton model using angular distributions of unpolarised Drell-Yan process. Early experiments clearly showed a strong violation of the Lam-Tung relation from their angular distributions. This violation may indicate that the QCD mechanism needs to go beyond collinear by including the intrinsic...
The HERMES Collaboration has measured charge-separated pion and kaon multiplicities in semi- inclusive deep-inelastic scattering using a 27.6 GeV electron or positron beam scattering off a hydrogen or deuterium target. The results are presented as functions of the Bjorken variable x, the negative squared four momentum transfer Q2, the hadron fractional energy, and the hadron’s transverse...
Recent Lattice QCD calculations have supported the long standing quark model expectation of many more excited states of the nucleon than have been experimentally observed. Detailed partial-wave analyses (PWA) fit to many polarization observables are required to search for such ”missing states. Furthermore, the separation of isoscalar and isovector couplings to isospin 1/2 resonances requires...
The HERMES experiment has collected a wealth of deep inelastic scattering data using the 27.6 GeV polarized lepton beam at HERA and various pure gas targets, both unpolarized and polarized. This allowed for a series of diverse and unique measurements. Among them are measurements that provide information on the three-dimensional structure of the nucleon both in momentum space and in mixed...
Permanent electric dipole moments (EDM) in elementary particles would violate CP-symmetry. The JEDI (J¨ulich
Electric Dipole moment Investigations) collaboration will measure the EDM of charged hadrons using a storage ring.
To keep the spin oscillation in phase with an external frequency, which is a requirement for EDM measurements in
magnetic storage rings, an active feedback system was...
Parity Violating Electron Scattering (PVES) is an extremely successful precision frontier tool that have been used for testing the Standard Model (SM) and understanding nucleon structure. Several generations of highly successful PVES programs at SLAC, MIT-Bates, MAMI-Mainz, and Jefferson Lab have contributed to understanding of nucleon structure and testing the SM. But missing phenomena like...
In the Spallation Neutron Source based neutron Electric Dipole Moment (SNS nEDM)
experiment, spins of polarized ultracold neutrons and polarized 3He will be manipulated in
a 0.3 - 0.5 K superfluid 4He bath. Measurements will be made using two different modes:
free precession and critical dressed spin. In the former, both spin species undergo a π/2
flip and then precess at their Larmor...
Transverse single spin asymmetries (SSAs) quantify the asymmetry of particle production relative to the transverse spin axis of a polarized hadron. SSAs have come to be recognized as a means of accessing QCD dynamics, both within initial-state hadrons and in the process of hadronization from partons. At √s = 200 GeV, heavy flavor single-spin asymmetries in proton proton collisions provide...
It has been recently pointed out that gluons can be linearly polarized even inside an unpolarized hadron provided that gluons should have non-zero transverse momentum with respect to the parent hadron. The effect of linearly polarized gluons on transverse momentum (PT ) and rapidity (y) distributions of J/ψ and Υ production is studied within the framework of transverse momentum dependent (TMD)...
Final results on the measurement of charged pion, kaon and unidentified hadron multiplicities in semi-inclusive deep inelastic scattering at the COMPASS experiment at CERN are presented and discussed. Measurements are performed using data collected in 2006 by scattering a 160 GeV muon beam off an isoscalar target, and cover a wide kinematic range defined by Q2 > 1 (GeV/c)2, 0.1 < y < 0.7 and...
Electron-proton scattering experiments have been providing a large amount of data on the proton structure function. However, because of the instability of the free neutron, fewer experiments have been able to study the neutron structure function. The BONuS collaboration at Jefferson Laboratory addresses this challenge by scattering electrons off a deuterium target, using a RTPC capable of...
Photocathodes with higher polarization and quantum efficiency (QE) can significantly enhance
the physics capabilities of electron accelerators. In this submission, we describe the characteristics
of strained GaAs/GaAsP superlattice photocathodes fabricated with a Distributed Bragg Reflector
(DBR). The distributed Bragg reflector (DBR) concept was proposed to enhance the QE...
The 2015 nuclear physics long-range plan endorsed the realization of an electron-ion collider as the next large construction project after FRIB. eRHIC, the Brookhaven realization of the electron-ion collider with its high luminosity ( > 10^33cm−2s−1), wide kinematic reach in center-of-mass-energy (45 GeV to 145 GeV) and high lepton and proton beam polarization provides an unprecedented...
Measurements of the ratio of the proton elastic form factors (µpGE/GM) using Rosenbluth separation and those using polarization-based techniques show a strong discrepancy, which increases as a function of Q2 . The contribution of hard two photon exchange (TPE) to ep scattering, which is neglected in the standard treatments of elastic ep scattering, is the most widely-accepted hypothesis for...
Generalized Parton Distributions (GPDs) provide a theoretical tool for 3D tomography of the nucleon in transverse coordinate- and longitudinal momentum space. The simplest and cleanest way to access the GPDs of the nucleon is Deeply Virtual Compton Scattering (DVCS). The inverse process, where the incoming photon is real and the outgoing one has a large ...
Few-nucleon scattering at intermediate energies (E/A ∼ 200 MeV) is one attractive approach to investigate the dynamical aspects of 3NFs, such as momentum and/or spin dependences. Direct comparison between the data and the rigorous numerical calculations based on bare nuclear potentials provides information of 3NFs. So far large 3NF effects are theoretically predicted and experimentally...
We investigate the spin structure of gluon transverse momentum dependent (TMD) correlators defined as Fourier transforms of matrix elements of nonlocal operator combinations. At the operator level these correlators include gauge links that bridge the nonlocality. In contrast to the collinear PDFs, the gauge links are no longer unique for TMD PDFs (TMDs). The single Wilson loop operator is...
Hydrogen and deuterium exists as two spin isomers, ortho and para, with the nuclear magnetic moments of the atoms either parallel or antiparallel. The spatial separation of the orthohydrogen molecules with respect to their nuclear moment in strongly inhomogeneous field of superconducting sextupole magnets is described. The scheme of the experimental setup and the results obtained under the...
Generalized parton distributions (GPDs) encoding multidimensional information of hadron partonic structure appear as the building blocks in a factorized description of hard exclusive reactions. The nucleon GPDs have been accessed by deeply virtual Compton scattering and deeply virtual meson production with lepton beam. A complementary probe with hadron beam is the exclusive pion-induced...
Analyzing powers for polarized neutrons exist only for thin hydrogen targets. Cross section and analyzing powers for np, for both elastic and charge exchange are known up to 29 GeV/c. No data are known to exist for thick analyzers, made of scintillator material. A scintillator polarimeter target is required to make a coincidence trigger for both reactions. The recoil proton of elastic...
Single transverse Spin Asymmetries (SSA) were first observed in hadro-production of inclusive charged pions at the ZGS at ANL in 1976. Over 40 years, these large asymmetries were found to persist in reactions at increasing center of mass energies in experiments at the AGS, FNAL and RHIC. Measurements of SSA in SIDIS at HERMES, COMPASS and Jefferson Laboratory were employed to separate...
The development of worldwide rare isotope beam facilities has brought many new insights in nuclear physics. In particular, novel structure in nuclei towards extreme isospin and spin has acquired great interest over the years for the challenges and implications it involves. Theoretically, covariant density functional theory (CDFT) has achieved great success in describing many nuclear phenomena...
We study the contribution of the twist-3 fragmentation function to the production of transversely polarized hyperons in unpolarized proton-proton collisions in the framework of the collinear factorization. Taking into account the constraint relations among twist-3 fragmentation functions which follow from the QCD equation-of-motion and the Lorentz invariance property of the correlation...
Spontaneous hyperon polarization has been a long standing issue for about 40 years. The so called polarizing Fragmentation Function(FF), D⊥ 1T(z, p2⊥), describes the production of a transversely polarized hadron from an unpolarized quark, where z denotes the fractional energy of the hadron and p⊥ the transverse momentum with respect to the fragmenting quark. The polarizing FF can be determined...
The transverse spin transfer to Λ hyperon can provide insights into the polarized fragmentation function and the transversity distribution which play important roles in understanding the spin structure of the nucleon. In 1997, significant spin transfer along the normal direction of the Λ production plane was observed at large xF by Fermilab E704 Collaboration. In this contribution we report an...
Semi-inclusive vector and pseudoscalar meson production in e
+e− annihilation at high energies is an ideal place to study three dimensional fragmentation functions, especially for the tensor polarization dependent part. We present the complete general kinematic analysis of this process and show that the cross section should be expressed by 81 independent structure functions, and give the...
Electron vortex beams provides an entirely new and unexplored degree of freedom for use in nuclear and particle physics- namely quantized orbital angular momentum (OAM). For example it may be used to explore the fundamental question of the contribution of of the orbital angular momentum of quarks and gluons to the spin of the proton. Such a source is under development at Jefferson Lab....
In this talk, we present an overview of the scientific opportunities that would be addressed by the China Electron-Ion-Collider (EIC). In the first phase the China EIC will be 3 ∼ 5 GeV polarized electron on 12 ∼ 23 GeV polarized proton (and ions about 12 GeV/nucleon), with luminosity 1 ∼ 2 × 1033cm− 2s− 1 . we will focus on discuss the EIC plan and its exciting physics po-tentials with the...
The chance to run and to optimize a fusion reactor with the use of nuclear–polarized fuel is discussed since many years. Furthermore the idea to construct a neutron-lean tokamak reactor still relies on our knowledge on the double–polarization cross–sections of the d–d reactions at the relevant very low energies, which have not yet been measured. Various theoretical predictions cover a wide...
An optical vortex forming a helical wave front along the direction of propagation of the beam has been actively investigated over the past few decades. Such vortices possess a phase singularity at the center of the beam, and the field strength there is zero. More importantly, it has been shown that an optical vortex which possesses a phase term exp(imφ) carries discrete values mħ of orbital...
Nuclear fusion has long been considered an ultimate solution for clean energy production. Despite decades of research, ignition, or self-sustained energy production, has been elusive. The use of spin-polarized fuel in a tokamak reactor would provide a significant boost. The cross section for the D + T → α + n reaction would be enhanced by 50% if the deuterium and tritium nuclei were fully...
Fragmentation functions describe the transition from asymptotically free, high energetic partons into final state hadrons. Since fragmentation functions are non-perturbative objects, they need to be measured experimentally. In particular electron-positron annihilation provides very clean input into fragmentation functions as no hadrons are involved in the initial state. The Belle experiment...
We discuss measurements of parity violating asymmetries in the DIS region at an EIC. With γZ interference in the electroweak processes, the parity violating asymmetries are associated with a new series of structure functions, FγZ1, FγZ3, gγZ1, gγZ5, which provide unique combinations of unpolarized/polarized parton distribution functions. We will present the projections of these structure...
In order to construct a future electron ion collider with high luminosity, a high average current and high bunch charge polarized electron source is under R&D at Brookhaven National Laboratory. A prototype of a high average current polarized electron funneling gun as an eRHIC injector has been built and in testing in Stonybrook University. Recently,...
Inclusive hadron production cross sections and angular distributions in e+e− collisions shed light on fundamental questions of hadronization and fragmentation processes. We present measurements of the Collins azimuthal asymmetries in inclusive production of hadron pairs, in the e+e− → h1h2X annihilation process, where the hadrons h1,2 (either kaons or pions) are produced in opposite...
We have carried out calculations demonstrating the benefits of having spin polarized fuel in future tokamak fusion reactors and the viability of testing spin polarized fuel in current tokamaks. The cross section for D-T (deuterium-tritium) fusion is increased by 50% when the nuclei spins are parallel to the tokamak guide field. In future magnetic confinement fusion reactor power plants the...
We present a framework to study the quark Orbital Angular Momentum OAM component of the proton spin, including the spin orbit interaction term. As shown recently in [1], quark OAM can be described in terms of either a Generalized Transverse Momentum Distribution (GTMD), or a twist three GPD, the two distributions being connected through a Lorentz Invariance Relation. A similar relation exists...
Hydrogen and deuterium exists as two spin isomers, ortho and para, with the nuclear magnetic moments of the atoms either parallel or antiparallel. The spatial separation of the orthohydrogen molecules with respect to their nuclear moment in strongly inhomogeneous field of superconducting sextupole magnets is described. The scheme of the experimental setup and the results obtained under the...
We discuss results for exclusive quarkonium photo- and electro production off the nucleon using the framework of generalized parton distributions (GPDs). A particular emphasis is on the gluon GPD Eg, which is related to the total angular momentum of gluons inside the nucleon. At present, Eg is basically unconstrained. On the basis of different models for Eg we estimate the transverse target...
The final nuclear physics experiments with “6 GeV CEBAF” were conducted in 2012 at which point
the accelerator complex was upgraded to double the beam energy and add a fourth experimental
hall. The accelerator upgrade was split into two periods, a six month period preceding the final 6 GeV
operations and an 18 month period post 6 GeV operations. Following completion of the upgrade work,
the...
Spin observables in nuclear structure and reaction studies have played a critical role in characterizing the nature of the nuclear force and dynamics. It is now well established that properties of nuclei at the limits of stability are very different from those found near the stability, representing the need to redefine the paradigms of nuclear structure physics. One such example can be found...
We have carried out calculations demonstrating the benefits of having spin polarized
fuel in future tokamak fusion reactors and the viability of testing spin polarized
fuel in current tokamaks. The cross section for D-T (deuterium-tritium)
fusion is increased by 50% when the nuclei spins are parallel to the tokamak
guide field. In future magnetic confinement fusion reactor power plants...
The A2 Collaboration at the Mainz Microtron MAMI measures photon absorption
cross sections using circularly and linearly polarized ’Bremsstrahlung’
photons up to an energy of 1.5 GeV and a polarized Frozen Spin Target. We
use a 4 π detection system with the ’Crystal Ball’ as central part.
One important experimental topic is the investigation of the baryons excitation
spectrum. Measurements...
In spite of its apparent simplicity, the Drell-Yan process continues to attract increasing levels of interest both in experiment and theory. Spin dependent Drell-Yan scattering provides unique access to transverse momentum dependent distribution functions of the nucleon, while the parton structure of unstable mesons can be probed from the unpolarized Drell Yan case.
Drell-Yan scattering...
The E-906/SeaQuest experiment has a new event reconstruction program available which will be used to perform future experiment analyses and cross-check various existing results. The focus of this poster will be on a dimuon mass spectrum and tracker efficiency study conducted with SQERP, focusing on dimuons produced via the Drell-Yan process. A mass spectrum study will isolate processes that...
The role of the anomalous moment in the geometric Clifford algebra of proton topological mass generation suggests that the anomaly is not an intrinsic property of the free space proton, but rather a topological effect of applying the electromagnetic bias field required to define the eigenstates probed by the magnetic moment measurement [1]. Quantum Interpretations try to explain emergence of the...
The longitudinal double-spin asymmetry (ALL) is spin-polarized p+p collisions provides insight into the gluon contribution to the proton’s spin by accessing the gluon helicity distribution ∆g. The PHENIX π0 and STAR jet ALL measurement show a non-zero asymmetries and hence indicate a nonzero ∆g in an NLO analysis. The STAR measurements of jet A LL in √s = 200 and 510 GeV polarized p+p...
One of the primary goals of the STAR spin program is to determine the spin-dependent gluon distribution, ∆G, of the proton. Recent measurements of the longitudinal double-helicity asymmetry, ALL, from inclusive jets place strong constraints on ∆G and, for the first time, find evidence for non-zero gluon polarization values for partonic momentum fraction x greater than 0.05. In contrast to...
The spin structure of the proton is of extreme complexity and remains one of the unresolved physics problems. The STAR experiment, located at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL), is performing a wide range of measurements to deconstruct the partonic contributions to the spin of the proton by analyzing polarized pp collisions. The Sivers effect...
We consider a 1+1 dimensional model for nuclei where the ‘nucleons’ are represented by a heavy-light system. This allows for the study of binding energies and quark distributions as a function of the separation between the nucleons. We find a significant shift of quark distributions towards smaller momentum.
Transverse single-spin asymmetries provide valuable information on the spin structure of the nucleon. At RHIC energies, heavy flavor production is dominated by gluon-gluon fusion, and the transverse single-spin asymmetry is sensitive to the tri-gluon correlations in the twist-3 collinear factorization. Study of this asymmetry for single muons from heavy flavor decays in the PHENIX experiment...
The COMPASS spectrometer at CERN took data in 2015 from a 190 GeV pion beam impinged on a vertically polarized proton target. The proton target consisted of two cells oppositely polarized with the polarization switched after each week. The goal of the 2015 COMPASS Drell-Yan data taking is to measure the Sivers amplitude from single spin asymmetries and therefore be able to determine a sign...
A fixed-target experiment using the LHC beams (AFTER@LHC) with a polarized target offers a unique opportunity to study the transverse spin structure of a polarized nucleon in a wide kinematical range. Recent studies have shown that a number of single transverse-spin asymmetries (STSA) are large enough to be precisely measured in the kinematical region accessible with AFTER@LHC, in particular...
We review the recent progress on what is known about the transverse spin structure of hadrons, in particular from observables that can be analyzed within a collinear framework. These effects have been around for 40 years and represent a critical test of perturbative QCD. We look at both proton-proton and electron-nucleon collisions for various final states. While the main focus is on...
Frozen spin polarized targets are perhaps the most complex and demanding target systems used in nuclear and particle experiments. The scattering sample is polarized in a very high magnetic field and at a sub-kelvin temperature, before being cooled to an even lower, millikelvin temperature for data taking. In some examples, the polarization and data acquisition even occur in different...
The Polarized Electrons for Polarized Positrons (PEPPo) experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-Z target.
A dedicated 3m long beam line was installed for...
I will review recent theoretical progress in our understanding of the longitudinal structure of the proton. My focus will be on the framework provided by perturbative quantum chromodynamics, and will include a discussion on the determination of helicity-dependent, collinear, parton distribution functions. Connections with nonperturbative models of nucleon structure will also be outlined. I...
The current understanding of the nucleon helicity structure will be reviewed based on the recent results from the Deep Inelastic Scattering experiments at DESY (HERMES), CERN (COMPASS) and Jefferson Laboratory, and polarized proton-proton collisions at RHIC. The advent of high luminosity and high center-of-mass energy Electron Ion Collider (EIC) will open new era in the nucleon helicity...
The measurement of the violation of parity symmetry in electron scattering has proven to be a powerful technique for exploring nuclear matter and for the search for new fundamental forces. A successful history of measurements has set the stage for a series of ultra high-precision measurements, to be made over the next decade, which will test the completeness of the Standard Model description...
Based on both the constituent quark picture and the instanton model for QCD vacuum, I will talk about the latest results about gluon distributions inside the constituent quark generated by the perturbative quark-gluon interaction, the non-perturbative quark gluon interaction, and the non-perturbative quark-gluon pion anomalous chromomagnetic interaction. The non-perturbative interactions are...
Transversely polarized e+/e- beams for precision energy calibration and (possi-bly) longitudinally polarized colliding e+/e- beams are critical topics for CEPC operation at lower energy ranges (Z pole and possibly WW threshold). A preliminary study of these aspects is first presented. Then, some Monte Carlo simulation results of a model ring lattice with relevant parameters will also be reported.
We try to classify the spectrum of the two-qubit Dicke model by calculating two quantum information measures of its eigenstates: the Wootters concurrence and the mutual quantum information. We are able to detect four spectral sets in each parity subspace of the model, which may attest to the existence of a symmetry or partial symmetry in the model. One of these sets is regular and given by the...
